According to new research from the firm, as charted here by Statista, smartwatches are the fastest-growing category of wearable devices, with annual sales expected to double (or more) by 2017. Wristband wearables like the Fitbit are expected to grow about 50%. Every other category is predicted to have slower growth.

Overall, Gartner expects consumers to buy about 180 million wearables in 2017, which is six years after Fitbit kicked off the modern wearables trend, and four years after Apple entered the market with the watch. By way of comparison, in 2013, six years after the iPhone kicked off the smartphone revolution, people bought more than 967 million smartphones.